The floating log was drawn behind the ship over a fixed time period in order to measure the distance travelled. The counter could measure enough miles to cover the maximum distance travelled by a ship in one day. The log has two distinct parts; a brass register, made by Walker, showing the distance recorded and the rotator, made by Reynolds, that spins in the water driving the counter. both parts are connected by a linked chain.
REgister has cylindrical brass body approx 1.75" (4.5cm) diameter containing registering mechanism with hardened steel bearings. Diastance is indicated by the three pointers on enamel plate as follows: graduated every 10 miles from 0-100; every mile from 1-10; every 1/4 mile from 1/4 -1. A brass sling and eye secured to the body enables it tobe attached to the taffrail.
Rotator has a cylindrical tapered wooden body, approx 1.75" diameter with three metal (alloy) fins. A towing eye is fitted to the tapered end. The two pieces of apparatus are connected by a length of linked chain, length 9" (22.9cm).